"They should check them as promptly as possible, and if they think there's an error, they should contact (their power company) as soon as possible."

"Consumers should probably compare their bills to their neighbors and compare their bills to prior months and prior years," Friedman adds.

"The very first piece of advice is that anybody who has question about bill should call us at 202-833-7500," Pepco Spokeswoman Myra Oppel says.

Smart meters should not change monthly bills other than eliminating the need for estimated billing.

"We are exchanging over 800,000 meters in the Pepco Region, so on occasion we may have an issue with a particular customer's account. If they notice that, we definitely encourage them to give us a call," Pepco's Marcus Beal says.

Beal says that Pepco takes photos of the old meters as they are removed, so that the information can be referenced if there are any issues with a later bill.

He says each billing issue is handled on a case-by-case basis.

Another thing that can throw homeowners' bill comparisons off is that not all bills cover the same length of time.

"We can have some bills that vary from 25 days of usage on up to about 35 days of usage," Beal says.

Those large billing cycle variations are slated to disappear for homeowners whose bills are tallied through a smart meter.

"We'll still have 21 billing days (each month), but we will have a consistent amount of days, plus or minus a few days, but it should be a lot more consistent than in the past," Beal says.

The smart meters also allow homeowners to see their detailed energy usage online.